1. Field of the Invention
The present invention relates to a refrigerator, and particularly, to a hinge assembly for a refrigerator door capable of improving an appearance and productivity by maintaining a horizontal state when a door is opened and of improving reliability of a product by smoothly supplying a lubricant.
2. Description of the Background Art
In general, there are various kinds of refrigerators according to structures and functions. Particularly, according to structures and positions of a door for opening and closing a storage space for food items, the refrigerators can be classified into as follows:
An one door type refrigerator in which a cooling chamber and a freezing chamber can be simultaneously opened and closed by using one door installed at a front of a main body; a two door type refrigerator in which the cooling chamber and the freezing chamber can be separately opened and closed by using two doors installed at the front of the main body in a longitudinal direction; a side by side type refrigerator in which the cooling chamber and the freezing chamber can be separately opened and closed by using two doors installed side by side at the front of the main body; a drawer type refrigerator in which a food storage space is slidingly drawn out of the front of the main body; a lift off type refrigerator in which a lid that can be opened and closed is installed at an upper surface of the main body; a refrigerator where the above-mentioned types are mixed; and the like.
Of those types, the drawer type and lift type are commonly employed for a refrigerator for ripening and storing Kimchi, which is called Kimchi-refrigerator. As for the Kimchi-refrigerator, when a newly made Kimchi is put in, a heater is operated to maintain a proper temperature and Kimchi is fermented at the proper temperature through successive ripening processes. Then, when the ripening processes for Kimchi are completed, components (compressor, condenser, expansion valve and evaporator) of a refrigerating cycle are operated to thereby circulate a refrigerant. In such a manner, the Kimchi refrigerator is maintained at a low temperature so as to be prevented from going bad.
FIG. 1 shows a general lift off type refrigerator.
As shown, in the general lift off type refrigerator, an inner case 13 is installed inside a main body 10 having an opened upper side, forming a freezing chamber (F) and/or a cooling chamber (C) for storing food items therein. A separate heater (not shown) and components of a refrigerating cycle are installed at a space between the main body 100 and the inner case 13 to thereby maintain the freezing chamber (F) and/or the cooling chamber (C) at a proper temperature.
A top cover 15 provided with two entrance/exit parts through which food items are brought in or taken out is installed at an upper surface of the main body 10, and two doors 20 that can be opened and closed are installed side by side to cover the entrance/exit parts of the top cover 15. Here, the door 20 that can be opened and closed has a rear end which is fixed to the main body 10 and the top cover 15 by a hinge assembly 30. The hinge assembly 30 operates to close the door 20 when the door 20 is at an angle less than a set angle, and stops to allow the door 20 to remain in an opened state when the door is opened to at least a set angle.
As shown in FIG. 2, hinge fixing portions 25 protrude rearward from both sides of a rear end of the door, and hinge fixing grooves 26 are formed on surfaces facing each other, of the hinge fixing portions 25, respectively. One end of each hinge assembly 30 is inserted in the hinge fixing groove 26, and then the hinge assembly 30 is screw-coupled to the main body through a coupling hole 37. Thereafter, a separate bracket (not shown) for decoration is installed to cover the hinge assembly 30 and the hinge fixing portion 25.
Particularly, as shown in FIG. 3, the hinge assembly 30 includes a shaft 31 having one end inserted in the hinge fixing groove 26, wherein a fixed cam 32 is integrally formed at the shaft 31; a moving cam 33 penetratingly installed at the shaft 31 and contacting with the fixed cam 32 formed at the shaft 31 in a cam type; a spring 35 penetratingly installed at the shaft 31, for elastically supporting the moving cam 33; and a housing 36 installed to enclose the shaft 31, the fixed cam 32, the moving cam 33 and the spring 35. A washer 34 is provided between the moving cam 33 and the spring 35, so that the spring 35 can be supported at the moving cam 33 through the washer 34.
Here, the shaft 31 is installed with its one end being inserted in the hinge fixing groove 26 to thereby rotate together with the door 20.
As for the moving cam 33, its outer circumferential surface is formed indented as a teeth shape, and stopping protrusions (not shown) are formed at the outer circumferential surface so as to be engaged with an inner circumferential surface of the housing 30.
The housing 36 is connected to a refrigerator main body. Namely, the moving cam 33 and the housing 36 are connected to each other, and the housing 36 is coupled to the refrigerator main body. For this reason, the moving cam 33 can move in an axial direction but cannot rotate.
At this time, the fixed cam 32 and the moving cam 33 make a relative motion by contacting with lines of each other in a cam type. Therefore, when the door 20 is opened or closed, a rotary motion of the shaft 31 and the fixed cam 32 is changed into a linearly reciprocating motion at the moving cam 33 by an interaction with the spring 35, to thereby control an opening/closing operation of the door 20. An extent to which the door is opened/closed can be controlled with a compressive force of the spring 35 and a gradient of curved surface of the fixed cam 32 and the moving cam 33.
However, the hinge structure for the conventional lift off type refrigerator door as described above is disadvantageous in that because two hinge assemblies are respectively installed at both sides of the door, it is difficult to coincide moving axes of the two hinge assembly with each other. If the moving axes of the hinge assemblies do not coincide with each other, both sides of the door are not horizontal but inclined when viewed from the front, thereby degrading the appearance.
In addition, in the conventional hinge structure for a door, a lubricant such as grease or the like is used so that a contact between the fixed cam and the moving cam in a cam type is smoothly made. Here, if the lubricant is solidified or leaked due to frictional heat or the like in operation, repetitive friction and abrasion undesirably occur between the fixed cam and the moving cam, and degradation of hinge operation performance such as noise generation occurs.
Also, because one end of the spring is installed and supported at a closed portion of the housing, the spring is compressed in operation, being supported at the housing. Accordingly, a residual stress is undesirably generated because of the accumulated fatigue of the spring, thereby weakening the strength.